In a building, a glass sheet (windows and doors) is a basic component.
Conventionally, in winter, there has been a problem of dew condensation due to difference between indoor temperature and outdoor temperature. The dew condensation on the glass not only causes bad visibility, but also causes a lower wall to become damp and moldy.
To solve such problems, studies have been conducted to develop technology for preventing dew condensation on a heat generating glass sheet due to difference between indoor temperature and outdoor temperature in winter in order to guarantee visibility, and various products have been produced using such technology.
A heat generating glass system uses a method for maintaining a heat generating glass sheet at a predetermined temperature or higher in order to prevent condensation thereon in winter. However, although condensation occurs only when the surface temperature of the glass is less than or equal to a dew point determined according to the temperature and relative humidity of an indoor area, the conventional heat generating glass sheet is configured to maintain the surface temperature of the glass constant, thereby causing undesired power consumption.